/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.phoenix.query;

import static org.junit.Assert.*;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Map;
import java.util.Random;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;
import org.apache.phoenix.end2end.NeedsOwnMiniClusterTest;
import org.apache.phoenix.jdbc.PhoenixConnection;
import org.apache.phoenix.jdbc.PhoenixDatabaseMetaData;
import org.apache.phoenix.monitoring.GlobalClientMetrics;
import org.apache.phoenix.schema.*;
import org.apache.phoenix.util.ReadOnlyProps;
import org.apache.phoenix.util.RunUntilFailure;
import org.apache.phoenix.util.ValidateLastDDLTimestampUtil;
import org.junit.BeforeClass;
import org.junit.Ignore;
import org.junit.Test;
import org.junit.experimental.categories.Category;
import org.junit.runner.RunWith;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.phoenix.thirdparty.com.google.common.collect.Maps;

@RunWith(RunUntilFailure.class)
@Category(NeedsOwnMiniClusterTest.class)
public class MetaDataCachingIT extends BaseTest {

  private static final Logger LOGGER = LoggerFactory.getLogger(MetaDataCachingIT.class);
  private final Random RAND = new Random(11);

  private boolean isLastDDLTimestampValidationEnabled =
    ValidateLastDDLTimestampUtil.getValidateLastDdlTimestampEnabled(config);

  @BeforeClass
  public static synchronized void doSetup() throws Exception {
    Map<String, String> props = Maps.newHashMapWithExpectedSize(1);
    // We set here a tiny cache to verify that even if the total size of the cache is just enough to
    // hold
    // system tables and Phoenix is still functional. Please note the cache weight for system tables
    // is set to
    // zero to allow insertion of system tables even when the cache reaches its maximum weight.
    props.put(QueryServices.MAX_CLIENT_METADATA_CACHE_SIZE_ATTRIB, "50000");
    props.put(QueryServices.CLIENT_CACHE_ENCODING, "object");
    setUpTestDriver(new ReadOnlyProps(props.entrySet().iterator()));
  }

  protected void createTable(Connection conn, String tableName, long updateCacheFrequency)
    throws SQLException {
    conn.createStatement()
      .execute("CREATE TABLE " + tableName
        + "(k INTEGER NOT NULL PRIMARY KEY, v1 INTEGER, v2 INTEGER, v3 VARCHAR, v4 Date, "
        + " v5 BIGINT, v6 SMALLINT)"
        + (updateCacheFrequency == 0 ? "" : "UPDATE_CACHE_FREQUENCY=" + updateCacheFrequency));
  }

  private void upsert(Connection conn, String tableName) throws SQLException {
    conn.createStatement().execute("UPSERT INTO " + tableName + " (k, v1, v1) VALUES ("
      + RAND.nextInt() + ", " + RAND.nextInt() + ", " + RAND.nextInt() + ")");
    conn.commit();
  }

  private void query(Connection conn, String tableName) throws SQLException {
    ResultSet rs = conn.createStatement().executeQuery("SELECT COUNT(*) FROM " + tableName);
    rs.next();
  }

  private String[] simulateWorkload(String testName, int numTables, int numThreads, int numMaxDML)
    throws Exception {
    String[] tableNames = new String[numTables];
    for (int i = 0; i < numTables; i++) {
      tableNames[i] = generateUniqueName();
      try (Connection conn = DriverManager.getConnection(getUrl())) {
        createTable(conn, tableNames[i], (i % 2) == 0 ? 0 : 100000);
      }
    }

    final CountDownLatch doneSignal = new CountDownLatch(numThreads);
    Runnable[] runnables = new Runnable[numThreads];
    for (int i = 0; i < numThreads; i++) {
      runnables[i] = new Runnable() {

        @Override
        public void run() {
          try (Connection conn = DriverManager.getConnection(getUrl())) {
            for (int i = 0; i < numMaxDML; i++) {
              upsert(conn, tableNames[RAND.nextInt(numTables)]);
              query(conn, tableNames[RAND.nextInt(numTables)]);
            }
          } catch (SQLException e) {
            throw new RuntimeException(e);
          } finally {
            doneSignal.countDown();
          }
        }

      };
    }
    for (int i = 0; i < numThreads; i++) {
      Thread t = new Thread(runnables[i]);
      t.start();
    }

    assertTrue("Ran out of time for test " + testName, doneSignal.await(120, TimeUnit.SECONDS));
    return tableNames;
  }

  @Test
  public void testSystemTablesAreInCache() throws Exception {
    simulateWorkload("testSystemTablesAreInCache", 10, 10, 10);
    try (Connection conn = DriverManager.getConnection(getUrl())) {
      ResultSet rs =
        conn.getMetaData().getTables("", null, null, new String[] { PTableType.SYSTEM.toString() });
      PMetaData pMetaData = conn.unwrap(PhoenixConnection.class).getMetaDataCache();
      while (rs.next()) {
        String tableName = rs.getString(PhoenixDatabaseMetaData.TABLE_SCHEM)
          + QueryConstants.NAME_SEPARATOR + rs.getString(PhoenixDatabaseMetaData.TABLE_NAME);
        try {
          pMetaData.getTableRef(new PTableKey(null, tableName));
        } catch (TableNotFoundException e) {
          fail("System table " + tableName + " should be in the cache");
        }
      }
    }
  }

  /*
   * TODO: The tables with zero update cache frequency should not be inserted to the cache. However,
   * Phoenix uses the cache as the temporary memory during all operations currently. When this
   * behavior changes, this test should be updated with the appropriate number of hits/misses.
   */
  @Test
  public void testGlobalClientCacheMetrics() throws Exception {
    int numThreads = 5;
    int numTables = 1; // test with only 1 table because we pick tables randomly in the workload
    int numMaxDML = 2;

    GlobalClientMetrics.GLOBAL_CLIENT_METADATA_CACHE_MISS_COUNTER.getMetric().reset();
    GlobalClientMetrics.GLOBAL_CLIENT_METADATA_CACHE_HIT_COUNTER.getMetric().reset();

    simulateWorkload("testGlobalClientCacheMetrics", numTables, numThreads, numMaxDML);

    // only 1 miss when the table is created
    int numExpectedMisses = 1;
    if (isLastDDLTimestampValidationEnabled) {
      // if we are validating last_ddl_timestamps,
      // region server will see 2 more misses when trying to update its cache
      numExpectedMisses += 2;
    }

    assertEquals("Incorrect number of client metadata cache misses", numExpectedMisses,
      GlobalClientMetrics.GLOBAL_CLIENT_METADATA_CACHE_MISS_COUNTER.getMetric().getValue());

    // (2 hits per upsert + 1 hit per select) per thread
    assertTrue(
      "number of total metadata cache hits (server+client) should be more than or equal to client cache hits",
      3 * numMaxDML * numThreads
          <= GlobalClientMetrics.GLOBAL_CLIENT_METADATA_CACHE_HIT_COUNTER.getMetric().getValue());
  }

  /*
   * The tables with zero update cache frequency should not be inserted to the cache. However,
   * Phoenix uses the cache as the temporary memory during all operations currently. When this
   * behavior changes, this test can be enabled.
   */
  @Ignore
  @Test
  public void testCacheShouldBeUsedOnlyForConfiguredTables() throws Exception {
    String[] tableNames =
      simulateWorkload("testCacheShouldBeUsedOnlyForConfiguredTables", 25, 10, 4);
    try (Connection conn = DriverManager.getConnection(getUrl())) {
      int hitCount = 0;
      for (int i = 0; i < tableNames.length; i++) {
        PMetaData metaDataCache = conn.unwrap(PhoenixConnection.class).getMetaDataCache();
        PTableRef tableRef = null;
        try {
          tableRef = metaDataCache.getTableRef(new PTableKey(null, tableNames[i]));
        } catch (TableNotFoundException e) {
        }
        if (i % 2 == 0) {
          // Cache should not be used for the odd numbered tables
          assertTrue(tableRef == null);
        } else if (tableRef != null) {
          hitCount++;
        }
      }
      assertTrue(hitCount > 0);
    }
  }
}
